Electronic Sputtering of Thin Conductors by Neutralization of Slow Highly Charged Ions

Charge states of slow ( $v\approx {0.3v}_{\mathrm{Bohr}}$) highly charged ions ( ${\mathrm{O}}^{7+}$, ${\mathrm{Ar}}^{16,18+}$, ${\mathrm{Kr}}^{33+}$, ${\mathrm{Th}}^{65+}$) have been determined after transmission through 10 nm thick amorphous carbon foils. Up to the highest charge states, ions reach charge state equilibrium in the foils within less than 21 fs. High yields of secondary ions are emitted from the foils as a result of the dissipation of tens to hundreds of keV of potential energy during ion neutralization. Positive secondary carbon ion yields increase strongly for $q>\mathrm{}25+$. Our results demonstrate, for the first time, the occurrence of electronic sputtering in the interaction of slow ions with thin conductors.